In the past, vocal rehabilitation of laryngectomies took place, for example, through learning of the so-called esophagus voice, for the creation of which the patient pressed air into his gullet (esophagus) and, through conscious relaxation of the pseudoglottis, was able to release the airstream which was then subject to articulation by his tongue and lips. Another possibility consisted of the use of so-called Servox devices, which were placed into the neck area and which vibrated. The vibration oscillations were subject to articulation through movement of the lips.
The acoustic pattern of the artificial voices produced in these ways does not correspond to a natural acoustic pattern in any way. Very deep and "raspy" artificial voices are produced. It is probably for this reason that use of these artificial voices, especially in female patients, is afflicted by an extremely high psychological inhibition threshold.
At the beginning of the 1980s, surgery could provide an improvement to the extent that a shunt could be inserted between the windpipe (trachea), which was otherwise surgically closed in the area of the pharynx, and the esophagus. So-called voice prostheses were placed into this shunt. The patient could breathe through this surgically created connection between the trachea and the environment through the so-called tracheastoma, which it was also necessary to create when using the earlier surgical techniques, and in more recent times, through the so-called tracheastoma valve, as it is described and claimed in EP-B-O 221 973, for example. If the patient now wanted to speak, he closed the tracheastoma with his finger or the valve closed automatically due to the higher air pressure, so that air could flow from the trachea through the shunt and into the esophagus.
A so-called voice prosthesis of this type is known from DD-275183 A1, for example. The designation of the one-way valve described therein as a voice prosthesis is certainly inappropriate. This valve does nothing except admit an air stream between the trachea and the esophagus, and prevent the entrance of food particles or saliva from the esophagus back into the trachea. The latter is of course extremely important, since otherwise complications such as pneumonia can occur. From a technical standpoint, however, the valve described in the cited reference merely closes off a different source of air when compared with the creation of the esophagus voice described earlier. The artificial voice created with the valve is also extremely deep in its frequency range, and is therefore very difficult to accept, especially for female patients.
DE-A-32 11 126 shows a so-called larynx prosthesis used in a shunt between the trachea and esophagus of a laryngectomized 10 patient, having an open, funnel-shaped expansion toward the tracheal end. This prosthesis does nothing except form a transition between trachea and esophagus, as has already been described in more detail. Similar prostheses are shown in U.S. Pat. No. 4,808,183, EP-A-O 279 484, and EP-A-O 222 509.
Another type of device is shown by DE-A-22 53 496 and JP-A-2-174843, for example. In these, devices are provided that have an extracorporeal tone-generating element in order to make use of an artificially generated frequency for speech modulation. The arrangement as an extracorporeal device is of course very burdensome for the patients, partly because these devices are visible to everyone with whom the patient converses.
Against this background, it is the object of the present invention to provide a voice prosthesis for use in the shunt between the trachea and esophagus of a laryngectomized patient, with which prosthesis the frequency range of the artificial voice can be adapted to the frequency range of the natural voice, and all parts of which can be implanted intracorporeally.